Purport

Hearing about the description of Yoga, Arjuna expressed his doubts about achieving perfection in Yoga. He said since the perfection of yoga depends very much upon controlling the mind and controlling the mind is like holding a violent wind.
Replying to his doubts, Bhagvan Shri Krishna accepted that controlling the mind is indeed difficult but can be controlled by using valid methods. The first method to control the mind is repeated and continuous practice. It is quite possible that at the beginning of practicing Yoga, one may find his mind wandering in thoughts. But one should not stop practicing Yoga. After continuous practice, the mind slowly comes under control.

Another method Bhagvan said to control the mind is the detachment from sensual gratification. As described in earlier Shloka, the presence of Rajas Guna is the main cause of physical passion and lust. Reducing the Rajasa Guna can help controlling senses. Having food fast, performing religious rituals, involving in service (Seva), reading Holy Scriptures, etc helps reducing the Rajasa Guna and hence the controlling passion in the human body. Reduction in passion reduces sensual desires.
By following the above two methods one can achieve control over the mind.